Naturalists’ Notes

Arboretum naturalists lead tours and record their observations throughout the seasons, gathering a valuable phenological record of Arboretum events. These notes also offer visitors a wealth of information on what you can see and enjoy at any particular time of the year.

Winter Water

January 22, 2017

Muskrat lodge near Icke Boardwalk

Ironically, this year’s Winter Water tour had to be shortened due to . . . well, WATER. Unseasonably warm temperatures have led to flooding on some Arboretum trails, and slipperiness on others. It’s difficult to get to Teal Pond, normally a mainstay of the Winter Water route. We made it there Sunday, but just barely.

Teal Pond is one small part of a wetland system covering more than 20 acres. The system is fed primarily by stormwater runoff—some 130 acre-feet of it annually—emanating from the higher ground of the West Beltline area and flowing in at three main input points. The eventual destination is Lake Wingra.

What’s an acre-foot? Simple: the amount of water it would take to cover one acre of land one foot deep. An acre, if you need a visual, is about the size of a football field.

While it might sound like quite a bit of water, that 130 acre-feet is actually less than ten percent of the total stormwater that courses in to the Arboretum. Much larger amounts come in at our far western and southern borders.

But the Teal Pond system (which includes Curtis Pond, Coyote Pond, and the unimaginatively named Pond 2) is a manageable chunk to describe and to walk to from the Visitor Center if trail conditions are good. On a day like this past Sunday, we settle for hiking to a few key areas and doing “show and tell” about the rest.

Teal Pond itself is representative of a prairie pothole—a water feature found in North American grasslands and sometimes called a “slough.” Pothole ponds are relatively small, shallow, and self-contained, as opposed to being connected to other wetlands by obvious rivers or streams. The water is of generally uniform temperature and relatively low oxygenation.

Because it is shallow, Teal Pond freezes solid in wintertime, meaning that fish should not be able to survive in it. This in turn makes it good habitat for frogs and many macroinvertebrates, since fish would be predators for them or their eggs. (It’s also great for painted turtles, which in warm weather are often seen there, clambering up on logs to bask in the sun and leaving trails through the duckweed as they swim about. Ah, summer.)

So that’s one manifestation of winter water—ICE. That’s most of what we saw on our trek. I always hope for some other forms to be in evidence—snowflakes, hoarfrost, ground fog, and the like—but ’twas not to be on this day. However, we did see liquid water without having to hike all the way to the springs. Good thing, as we wouldn’t have made it that far anyway!

While in the Teal Pond area, we heard at least one male black-capped chickadee singing his two-note territorial song. I always think of it as “See me, here sweetie!” Hearing this jaunty song is a reminder that spring, and breeding season, will return.

We cautiously made our way into Gallistel Woods to see two other components of the Teal Pond wetland system. First, the (unnamed) temporary pond just to the west of the Icke Boardwalk. This is a vernal pond, normally water-filled only in the first half of the year. By mid- to late summer it dries up completely. This schedule makes it better habitat for some organisms than others. Theoretically, crustaceans, mollusks, certain insects, and salamanders make use of vernal ponds at critical points in their life cycle. If I ever see a salamander in this particular pond, you’ll be the first to know!

The Icke Boardwalk traverses a cattail marsh (which besides cattails, also includes horsetails, water plantain, and many other plant species). Notable in this marsh this year are the muskrat houses! We started seeing their construction last fall. Muskrats are well known in the Arboretum, but this is the first time in my memory that we’ve had a den so easy to see and to point out to visitors.

In fact one November day just before sunset I stood on the boardwalk, transfixed, as a muskrat moved to and fro in the vegetation, adding to one of the mounds. I never glimpsed the creature itself, just saw evidence of where it went and what it did. First a line of plants waved gently as the animal swam underwater amongst them. Then one or two stems shivered mightily, and fell, as they were gnawed down from their base. Next the route back to the den was retraced, and finally I saw the mound being pushed up from the inside as the muskrat worked to enlarge its home.

I wonder what impact the muskrats’ presence might have on the sandhill cranes which sometimes attempt to nest in this very same area. Wait and see, wait and see.

Normally in January, we’d be seeing ice below the boardwalk, not open water. But this has not been an ordinary winter so far, and thus there has been much melting. Cypress knees stood pinkish and knobby above the liquid surface; perhaps if I’d hunkered down and peered very closely, I’d have seen snow fleas floating.

Water flows through the Icke Boardwalk area to the north, threading through a culvert under the Arboretum road and eventually emptying into Lake Wingra.

With better trail conditions we can hike to at least one of the Wingra springs—to view water that is in motion year-round—but given the slow going on Sunday, we had to be content with seeing those on a map. If you’re planning to hike in the Arboretum any time soon, I suggest good waterproof boots, and ice treads.

I leave you with Loren Eiseley’s words from his 1946 book The Immense Journey: “If there is magic on this planet, it is contained in water . . . its substance reaches everywhere; it touches the past and prepares the future; it moves under the poles and wanders thinly in the heights of air. It can assume forms of exquisite perfection in a snowflake, or strip the living to a single shining bone cast up by the sea.”